1. Field of the Invention
The present invention relates to a so-called outdoor portable gas cooking stove, and more particularly, to a burner structure of a portable gas cooking stove.
2. Description of the Related Art
FIG. 1 shows an example of a portable gas cooking stove known in the art.
Normally, the portable gas cooking stove 10 includes a gas cartridge 11 filled with compressed combustible gas, and a gas burner 12 mounted detachably on the gas cartridge 11. The gas cartridge 11 and the gas burner 12 are coupled to each other in a hermetically sealed condition through a gasket 13.
The gas burner 12 is comprised of a plug fitting 14 which is connected to the gas cartridge 11 and through which combustible gas supplied from the gas cartridge 11 passes, a gas flow adjusting spindle 15 which adjusts a degree of opening of a gas passage formed inside the plug fitting 14 to thereby adjust a flow of the combustible gas passing through the plug fitting 14, a burner head 16 with a number of openings 16a formed on a surface thereof, a mixing tube 17 connecting the plug fitting 14 to the burner head 16, kettle holders 18 that are fixed on the mixing tube 17 and extend over the burner head 16, and an igniter 19 mounted on a support 19a.
The combustible gas is filled in the gas cartridge 11 in a pressurized condition. Hence, when the gas passage is opened by the gas flow adjusting spindle 15, the combustible gas in a pressurized condition enters the mixing tube 17 from the gas cartridge 11 through the plug fitting 14. Thus, the combustible gas enters the mixing tube 17 with a gas flow thereof being adjusted by the gas flow adjusting spindle 15.
The mixing tube 17 is formed with a number of openings 17a (only one of them is illustrated in FIG. 1). External air is absorbed into the mixing tube 17 through the openings 17a by virtue of negative pressure produced when the combustible gas passes through the mixing tube 17. The combustible gas is mixed with air entering the mixing tube 17 through the openings 17a, into a gas mixture of the combustible gas and air.
After the gas mixture enters the burner head 16, the gas is discharged through the openings 16a, and is ignited by the electric igniter 19 located in the vicinity of the burner head 16.
The flame of the burning gas mixture heats an object to be heated such as a pan, kettle, food, etc., put on the kettle holders 18.
In general, outdoor appliances, not limited only to portable gas cooking stoves, are required to be small. Regarding a portable gas cooking stove, the gas cartridge 11 cannot be fabricated smaller in size than a practical limit determined to ensure a volume of gas to maintain a gas-burning time required for practical use. Consequently, in a portable gas cooking stove, miniaturization has been focused mainly on the gas burner 12, and more particularly, on the burner head 16.
However, if the burner head 16 is simply reduced in size, a flow of the gas mixture may exceed the proper gas burning rate, because a volume of the burner head 16 becomes smaller relative to a gas flow from the gas cartridge 11, resulting in a greater rate of the gas mixture discharged through the openings 16a of the burner head 16.
If the gas mixture is discharged at a great rate, the gas mixture is rarely ignited by the spark generated by the igniter 19, resulting in incomplete combustion of the gas mixture.
In addition, in the gas burner illustrated in FIG. 1, the igniter 19 is supported only by the support 19a, resulting in that the igniter 19 cannot be stably fixed relative to a gas flow of the gas mixture discharged through the openings 16a. This also causes incomplete combustion of the mixture gas.